A serializer/deserializer (SERDES) is a pair of functional blocks commonly used in high speed communications to perform on-chip conversion of a high speed serial data stream into multiple parallel low speed data lines. These blocks convert data between serial interfaces and parallel interfaces in each direction. Such data is received and transmitted in the form of electric signals. An electric signal received by a serializer/deserializer may undergo various forms of signal processing before being transmitted. As such, a serializer/deserializer may comprise a receiver frontend to accomplish various portions of the signal processing. Such processing may include equalization, common-mode voltage adjustment, electrostatic discharge (ESD) protection, and termination of signals, for example.
The term “equalization” refers to the process of boosting high frequency contents of an input signal in order to compensate for frequency dependent losses in the channel. The term “common-mode voltage adjustment” refers to the process of optimizing a common-mode voltage for a channel by supplying DC current to the channel. A system may be able to provide common-mode voltage adjustment for various ranges of common-mode voltages. The term “ESD protection” refers to a system's ability to protect against various electro-static events during chip and part assembly, and product use, that may potentially cause permanent damage to the circuits. “Termination of signals” refers to the process of reducing or eliminating unwanted reflected signals caused by an impedance mismatch between silicon chip inputs (e.g., pads) and the channel.